Charles a



(No Model.)

0. A. RANDALL.

ELBOTRO MAGNETIC RELAY.

Patented Feb. 21,1882.

\A/ITN E5= IQ JEN- 'm F'-\ 25m (55. MOZWW 0412011 JJZZ, 7 y

UNITED STATES PATENT OEEIQE.

CHARLES A. RANDALL, OF NE\V YORK, N. Y.

ELECTRO-MAGNETIC RELAY.

SPECIFICATION forming part of Letters Patent No. 254,045, dated February21, 1882. Application filed April 5, 1880. (N0 model.)

To all whom it may concern:

Be it known that I, CHARLES A. RANDALL, a citizen of the United States,residing at New York,in the county of New York and State of New York,have invented new and useful Improvements in Electro -Magnetic Relays,of which the following is a specification.

This invention relates to that class of telegraphic instrumentstechnically named relays, which are included in main-line circuits andarranged to control the flow of batterycurrents over local circuits.

As heretofore constructed a relay has generally consisted of anelectro-magnet having its armature secured to a lever on a rock-shaltmounted in suitable bearin gs, a vibratory movement of said lever beingcaused by the attraction of the armature by the magnet and theretractile force of an adjustable spring acting alternately. Themovement ofthe lever is usually limited by one or more adjustablestopscrews, one of raid screws serving as a contact terminal of anelectric circuit of which the vibratory lever is the other terminal, sothat by the vibration of said lever the circuit is alternately made andbroken.

The object of my invention is to simplify the construction of relays andobviate the trouble and loss of time occasioned by the frequentnecessity for adjustment of the stop-screws and rot 'actile spring ofthe armaturelever.

To this end it consists in, first, the combination, in anelectromagnetic relay, of thcelastic or spring arm constituting oneterminal of the apparatus, the carbon or other suitable buttonconstituting the other terminal, and with which the elastic arm is inpermanent contact, an elect-ro-magnet the attraction of which draws theelastic arm against the carbon button, and suitable electricalconnections whereby the terminals may be held in contact with a varyingforce an d the current correspondingly varied, the spring-arm affordingthe proper elasticity of contact, as hereinafter set forth second, thecombination, in an electromagnetic relay, of the elastic or yieldinglever, a suitable fixed terminal or button in permanent contact with thelever, an electro-magnet which draws the lever against the fixedterminal, and a screw for adjusting the magnet, as hereinafter setforth.

In the accompanying drawings, Figure 1 is a side elevation of atension-changing relay constructed according to my invention, and Fig. 2a perspective view of the same.

The letterAdesignates an electro-magnet, tothecross-baraofwhichissecuredascrew-rocLB, passing loosely through anaperture in a bracket, 0, and havingupon its outerportion athumbnut, D.Between the bracketand thecross-ba-r of the armature thc screw-rod B issurrounded by a spiral spring, E, the ends of which bear againstsaidbracketandcross-bar, respectively. By means of the screw-rod, when thenut is screwed inwardly upon it, the magnet is drawn away from thearmature F, and by means of the spring E, when the nutis screwedoutwardly, the magnet is moved toward said armature, so that the forcewith which the magnet acts upon its armature may be controlled asdesired, or the distance through which the magnetic influence of thecore acts upon said armature may be regulated in accordance with thestrength of the current which may be passing over the coils of themagnet. The armature F is secured to an elastic metallic lever, G,projecting from a metallic arbor, h, mounted in bearings in the metallicstuds 1'. The top or free end of the elastic lever G rests permanentlybut loosely against a carbon button, K, supported by a post, l, and saidcarbon button forms one terminal of an electric circuit, (usually alocal circuit at a telegraph-office,) the elastic lever being theotherterminal and connected with the battery through its arbor and thebearings thereof and a suitable wire. The electro-magnct is included inthe main or line wire circuit, and when the strength of the current uponsaid main circuit is varied by any suitable means the action of themagnet upon its armature causes corresponding vibrations of the pressurewith which the elastic lever bears upon the carbon button. The maincircuit should be constantly closed, but so regulated that normally thepressure between said button and lever will be very slight, andconsequently but a very light current will flow over the local circuit,not sufficient to produce any mechanical operation of instrumentsincluded in said local circuit; but when the strength of the currentupon the main circuit is increased and the pressure between the clasticlever and carbon button increased correspondingly the current of thelocal battery flows freely over its circuit in such quantity as tooperate the included local instruments, the increase and decrease ofpressure thus resulting in the same effect which is produced by themakes and breaks of the ordinary relay.

1 am aware that heretofore a relay in which the current has been variedby varying the resistances by pressure of a substance interposed betweenthe terminals of the relay has been shown and described; but theorganization of apparatus thus described is practically defective and isdifferent from that claimed herein.

What I claim is- 1. The combination, in an electromagnetic relay, of theelastic or spring arm constituting one terminal of the apparatus, thecarbon or other suitable button constituting the otherter- Ininal, andwith which the elastic arm is in permanent contact an electro-magnet theattraction of which draws the elastic arm against the carbon button, andsuitable electrical connections whereby the terminals iuaybeheld incontact with a varying force and the current correspondingly varied, thesprin g-arin aftbrdin g the proper elasticity of contact, substantiallyas and for the purpose set forth.

2. The combination, in an electromagnetic relay, of the elastic oryielding lever, a suitable fixed terminal or button in permanent contactwith the lever, an electro-magnet which draws the lever against thefixed terminal, and ascrew for adjusting the magnet, substantially asand for the purpose set forth.

In testimony whereotI have hereunto set my hand in the presence of twosubscribing witnesses.

CHARLES A. RANDALL.

Witnesses:

P. G. RANDALL, OLE H. lloLBERG.

